Active Galactic Nuclei – the Physics of Individual Sources and the Cosmic History of Formation and Evolution

In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present under-standing of the inner workings of the central engines, most likely accreting black holes with masses between 106 and 1010M. We highlight recent results concerning the jets (collimated outflows) of AGNs derived from X-ray observations (Chandra) of kpc-scale jets and γ-ray ob-servations of AGNs (Fermi, Cherenkov telescopes) with jets closely aligned with the lines of sight (blazars), and discuss the interpretation of these observations. Subsequently, we summa-rize our knowledge about the cosmic history of AGN formation and evolution. We conclude with a description of upcoming observational opportunities.